An agreement to delay a mussel survey clears the way for construction of a new bridge over the Wapsipinicon River.

Chronic high water this spring has prevented the survey, which had been a prerequisite for the $1.7 million project to begin.

Mike Vermace, general manager of Minnowa Construction of Harmony, Minn., said work could begin as soon as Wednesday, which would entail immediate closing of the high-traffic bridge.

Vermace said the contract called for the mussel survey to be conducted as soon as the river flow fell below 400 cubic feet per second at the Tripoli gauge — a condition that has yet to occur.

To expedite the stalled project, the Department of Natural Resources last week agreed to a post-construction survey that would identify damaged and destroyed mussels and assess appropriate mitigation costs.

DNR fisheries biologist Dan Kirby called the agreement a compromise.

“The pre-construction survey would have been preferable, as it would have allowed relocation of the affected mussels, but Mother Nature just would not cooperate,” Kirby said.

Another factor supporting the compromise, he said, was that a survey a year ago just upstream from the bridge found few mussels.

The Buchanan County supervisors on April 1 signed an agreement with IIW, PC, a Dubuque engineering firm, to conduct the survey and relocate affected mussels at a cost not to exceed $57,000.

“In this situation, hopefully there won’t be many mussels,” IIW employee Gretchen Bockenhauer said Monday after a cursory search near the bridge found none.

Buchanan County Engineer Brian Keierleber said the bridge closure will inconvenience many motorists.

More than 2,460 vehicles cross the bridge each day, according to Department of Transportation statistics, he said.

In addition to local traffic, many vehicles cross the bridge as part of a shortcut between Interstate 380 and the four-lane Highway 20.

The bridge is considered such a key transportation link that the county has, for the first time, incorporated rapid completion incentives in the contract, Keierleber said.

According to the contract, Minnowa Construction will be rewarded with $10,000 per day for each day fewer than 120 days it takes to complete the bridge or penalized $10,000 per day for each day over 120 days.

Keierleber said detour signs have been posted but will remain shrouded until the bridge actually closes.

The official detour route crosses the river at Independence, with the bridge in Troy Mills serving as an alternate route.

Federal funds will pay 80 percent of the project’s cost with the city and county splitting the remaining 20 percent, Keierleber said.

An engineering study determined that it would be more economical to replace the 1959 bridge than to rehabilitate it, he said.

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